1. Field of the Invention
The present invention relates to transmission shift control mechanisms, also commonly referred to gear selector mechanisms, for use in manually controlled transmissions. In particular, the present invention relates to directly mounted master shift control mechanisms which are relatively lightweight, simple and inexpensive.
2. Description of the Prior Art
Manually controlled change gear transmissions of both the sliding gear and/or sliding clutch type, and the shifting mechanisms for selective shifting thereof, are well known in the prior art. In recent years there have been many improvements relating to the shifting mechanisms for such sliding gear and/or sliding clutch type manual transmissions. However, there continues to be a need to provide a relatively inexpensive, relatively lightweight, simplified shifting mechanism for establishing desired shifting movement, for providing adequate feel for the operator to establish that a correct gear has been selected and for providing an optimized mechanical advantage and shift lever travel for both the "gear selection" and "gear engagement" modes of operation of the shift lever. Additionally, it is desirable to improve the simplicity and reliability of the interlock mechanisms utilized with transmission shifting mechanisms having a plurality of axially movable shift rails therein which interlock mechanisms prevent axial movement of more than one shift rail at a given time. There is also a continuing need to improve the reliability and serviceability of such transmission shifting mechanisms.
The use of rectangularly cross-sectionally shaped shift rails, also referred to as flat shift rails and flat shift bars, to simplify and reduce the expense of shift bar housing assemblies is known as may be seen by reference to U.S. Pat. No. 4,273,004, hereby incorporated by reference.
The use of pin and/or ball type interlock mechanisms is well known in the prior art as may be seen by reference to U.S. Pat. Nos. 3,387,501; 4,120,212 and 4,296,642, hereby all incorporated by reference. While such interlock mechanisms are functionally acceptable, they are not suited for all types of shifting mechanisms and/or tend to be complicated and/or expensive to manufacture and/or assemble.
Mechanisms for providing an operator with a feel for varification of proper shift rail selection when manually shifting a gear shift lever of a mechanical transmission by use of resilient yieldable means is known in the prior art as may be seen by reference to U.S. Pat. Nos. 3,934,485 and 4,022,078 both hereby incorporated by reference. While such prior art mechanisms are suitable for certain purposes, they tend to be complicated and/or expensive to manufacture, assemble and/or service and/or do not provide the operator with a feel positively indicating correct selection in a shift bar housing assembly having three, four or more shift rails.
Directly shifted transmissions wherein the transmission shifting mechanism comprises a shift lever or the like which is mounted directly in a tower assembly mounted to the transmission housing and wherein the transmission shifting lever directly engages the shift rails of the transmission shift bar housing are well known in the prior art as may be seen by reference to above mentioned U.S. Pat. No. 4,273,004. While such prior art mechanisms are well suited for certain situations, they were not well suited for certain situations, such as heavy duty synchronized transmissions, wherein a much greater mechanical advantage is required for gear engagement movement (i.e. to frictionally engage the synchronizer clutches) of the shift lever than is required for gear selection movement of the shift lever.